Increase the dependency on rubygems to rubygems 1.3.1. This has been the stable version since January 2009, and we don't have older versions in the tree anymore. Two benefits: a) we can simplify the installation call again in this eclass, and b) we can be sure that "development" style dependencies of a gem will be ignored when installing it.

Handle the installation of gems differently when using rubygems >= 1.3.0.
Specifically we use our own custom --sandbox-fix option to make sure that
finding dependencies still works even when using a sandbox installation.
Thanks for Alex Legler (a3li) for the work on this.

Updated rubygems dependency to be >= 0.9, in order to remove obsoleted workaround for gem not returning a proper exit code. This fixes bug #202688. Removed unneeded setting of S. Re-ordered src_* functions to be in order. Use long command line options for gem, to be more clear what it's doing.

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